The cylinders in an internal combustion engine can be disabled in order to reduce fuel consumption. This may be accomplished by cutting off the supply of fuel to selected cylinders, particularly to save fuel under light engine load conditions. This increases the load on the other cylinders and provides some pumping loss reduction, but still requires pumping work to move the air flow through all the cylinders. Another method of cylinder disablement includes disabling or maintaining the intake and exhaust valves of the cylinder in a closed condition, which further reduces pumping work over simply providing a fuel cutoff to the deactivated cylinders.
Exiting and/or entering a cylinder deactivation event in which the intake and exhaust valves are closed can create operating inefficiencies and lags in responsiveness of the engine. Therefore, further improvements in cylinder deactivation systems and techniques are needed.